Just a thought as this route could include the voyager as the base unit with Cross Country, with the GWR licence back they can be used on the Didcot - Banbury services and depending on the era it could possibly include the 387 seen on the GWE remaster with also HST services to Oxford as well as AI services continuing on from Didcot and Oxford to Worcester. This also adds room for a possible cargo line addon for car carrier functionality for Morris Cowley MAT as well as plenty of freight functionality at Hinksey yard and Didcot yard as well as plenty of functionality for the new Cargo line 3 for the intermodals passing through as well as the 4th one for Bicester MOD services passing through. The re-skinned 166 for the debanded chiltern seen on the Mildmay line can also be used at Oxford and also at Banbury
A route with great variety and the renewal of the GWR licence removes one obstacle. However the biggest remaining one is Cross Country so unless you set the route back in BR days you are not going to see the lions share of traffic.
Unbranded would work fine, do Grand Central have any more Voyagers? But then again would they even allow DTG to record?
That’s the point, without access to the prototype DTG would struggle to get the information needed to represent the trains in TSW.